Flexible Circuit Board Rounded Connection Stress Relief
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Solution Overview
Problem
Flexible circuit boards in chip on film (COF) bonding technology face mechanical stress issues due to sharp corners in wire connections, leading to high stress concentrations and increased likelihood of joint portion failure when bent.
Innovation Solution
The flexible circuit board design incorporates rounded concave and convex sections in connection portions between inner and outer leads to alleviate mechanical stress, with specific curvature radii and configurations that reduce stress concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the flexible circuit board is bent to enable positioning flexibility, then the adaptability of the circuit board is improved, but the mechanical stress concentration at sharp corners increases leading to joint portion failure
Solution Approach 1:
The patent applies curvature by replacing sharp corners with rounded corners at the joint portions where inner leads connect to outer leads. This rounding eliminates stress concentration points that would otherwise occur at sharp angles during bending, thereby maintaining joint reliability while preserving the flexibility and adaptability of the circuit board for various positioning configurations.
2Reliability
If rounded corners are added to alleviate stress concentration, then the reliability of joint portions is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent applies local quality by implementing rounded corners only at specific critical locations (joint portions where inner leads connect to outer leads) rather than throughout the entire circuit board. This localized approach selectively improves reliability at stress-prone areas while minimizing the overall structural complexity and maintaining simplicity in other regions of the circuit board.
Data Source
AI summary
A flexible circuit board uses a specific structure to alleviate mechanical stress thereof. The flexible circuit board has a flexible film, a plurality of inner leads, a plurality of outer leads, and a plurality of connection portion. Each of the connection portions a corresponding one of the inner leads with a corresponding one of the outer leads. A first width of the inner leads is greater than a second width of the outer leads. Due to rounded concave sections and rounded convex sections of the connection portions, if the flexible circuit board is bent, the mechanical stress around corners of joint portions of the connection portions with the inner leads and the outer leads could be alleviated.